Does it make sense to calculate Cpk on properties like compressive strengths and moduli?

I mean, the calculation of such indirect properties is based on different single measurements:

- dimensions (length/ width/ thickness)

- mechanical tests

Thanks in advance for your help

Samuele]]>

Thanks for the advice.]]>

The relationship between normal tolerance intervals (k factors) and process capability index (Ppk) is as follows: k = 3 x Ppk or Ppk = k/3.

In my work I have to assess process validation documentation and recently I have seen this statement in use from a number of external suppliers. My google fu has failed me on finding a source, none of the suppliers can provide one ( SOP's were written...

Tolerance interval and Ppk]]>

I have experience in automotive quality, where we dealt with components/parts that could be physically measured.

So how do you apply the same quality control concept in a chemical industry, specifically polyurethane (raw material)?

Our products are supplied in 2 parts of chemical (1 is Isocyanate, the other is a blend of polyols and additives).

All we do in house is blend certain chemicals and supply them to our customer.

So...

Process capability study in Chemical industry]]>

There are three inputs that are statisticaly significant (p value = 0,000) and there is no multicolinearity.

What is difference between;

- F-Value

- Contribution

- Coef or coeded Coef

Which values should be considered when assessing the most significant predictor? I mean which one should be adjusted "as a first" in order to optimize the process.

Could be please give me the explanation to the attached files.]]>

I've a lack of knowledge than is blocking my analysis.

We register the efficiency of a process, measured as percentage.

Requirement is that minimum values has to be >95%, our data populations are distributed between 97% and 100%

I was required to define a ppk of this variable.... but I can't really approach it because I don't know how to handle cases where there is a physical upper (or lower) limits.

Could someone...

cpk on non-normal distribution (limited intervals)]]>

I choosed the PLS Regression - with Cross Validation.

I have included all the predictors without checking significance - without 2-way interactions.

The results are:

R-sq - 65% with 4 components

R-sq (pred) - 0%

R-sq is the percentage of variation in the response that is explained by the model.

R-sq (pred) -...

R-sq vs. R-sq (pred)]]>

A couple of questions:

- What is the name for this kind of distribution, where any integer is allowed but not the probability is not uniform?
- If this is indeed not normal, do I do a transform? I used...

Capability for discrete data, not sure what distribution is called]]>

So, pull test, spec = 20 lbs. Actual values, 100+ lbs. limit of the test gage is 100 lbs.

Engineer #1 suggests treating it as attribute data, which would require additional samples.

Engineer #2 suggests recording failure as 100 lbs, which is 5x spec, but does give a false standard dev.

Excluding purchasing a new test gage, which is $1500, other suggestions or justifications?

Thanks!]]>

2. Regarding collecting data for SPC from the specific process, I have another question.

What is the best sampling frequency for collecting data for conducting SPC.

Generally we apply rule: 5 pieces per each hour of manufacturing, overall 25 hours = 125 pcs.

Is it a must, or other rules can...

Capability for one sided specification]]>

The process X should be introduced to the machine 2 (as backup).

Every run is expensive and time consuming. This is why there is no possible to collect data easily.

--------------------------

How could be evaluated, that the process X on the machine "works well"? (Cpk>0.8)

What sample size...

evaluation of the process produced on the another machine]]>

- When to use "Quantile Cpk"

View attachment 586]]>

One of the powerful things about it, is you can assign "sliders" to terms of equations, pretty much at will....

Capability Models in Geogebra]]>

Johnson Tranformation Across lots for Process Capability]]>

Can't we just do the study on the collective output of the 12 value streams?

It's a hard problem to...

Capability and Parallel Processes]]>

I would like to perform a capability analysis in Minitab - I ran the normality test and got the result, that my data are not normal distributed.

I believe that the measurement data are correct and there is no reason to improve the process.

I would like to have my data transformed, but it doesnt work.

I have run an Individual Distribution Identification with all distributions and transformations, but any of them increased the p-value above 0,05.

May I run the Nonnormal Capability...

Capability analyses with nonnormal data]]>

My husband is studying for the ASQ CQE exam. He is stumped on the question below, from the ASQ sample test. He was able to figure out the Exponential Life subsystems, but can't find the formula to determine the Weibull. Forgive me if I'm writing this wrong. He's the quality expert... I'm the Google expert!

Question:

A series system contains three subsystems with the following distributions.

Subsystem | Distribution

1 | Exponential life; MTBF = 10,000 hours

2 | Weibull...

Reliability of subsystems, including Weibull]]>

The specific example I am working with is a water heater is controlled by PID system (non-normal or tampering) which constantly corrects for "error" from set point. Heated water from this system is cooling...

Assuming Normality or Other Distribution]]>

How do to select USL and LSL limits?

For example,

I have observation results of 30 Re is 3.43, 3.27 ,3.19, 3.17,3.17, 3.19, 3.19, 3.24, 3.1, 3.12 ,3.25, 3.2, 3.35, 3.2, 3.2, 3.22, 3.23, 3.18, 3.19, 3.31, 3.18, 3.08, 3.18, 3.17, 3.23, 3.19, 3.25, 3.26, 3.23, 3.18

mean = 3.2117, STD = 0.07

Company datasheet provided for Re is 3.08 and production tolerances +/- is 7.50%

——–

to find Cpk how do I calculate USL and LSL values?]]>